Method of producing oxidation inhibitors



May 5, 1942.

WASHER.

FQJEAcr'IQM CHAMBER FEE/ EATIN J. A. TlLTON METHOD OF PRODUCINGOXIDATION INHIBITORS Filed March 4, 1939 A c /.D

7122.4 TING CHAMBER cHAMBaz 12 H 1 5 gig-2 0 0071- 71 625 .25 5.. H

CHARGE OIL IIVLE 7' generate the catalyst.

Fatented May 5, 142

' METHOD (PF PRQDUCING Q ACTION ETORS Joshua A. Tilton, Baton Rouge,La., asslgnor to Standard Oil Development Company, a corpo-.

ration of Delaware Application March 4, 1939, Serial No. 259,781

4 Claims.

It has heretofore been proposed to, form gasoline by crackinghigher-boiling hydrocarbons in the presence of a catalyst such asnaturally active or activated clays or the like. According to one of themethods employed, the oil to be cracked is passed in vapor form througha reaction zone containing said catalyst maintained at the requiredcracking temperature.v When operating in this manner, the catalystgradually becomes fouled with carbonaceous deposits requiring periodicinterruption of the cracking operation to re- The regeneration isaccomplished by passing an oxidizing gas through the catalyst to burnthe deposits.

I have found that gasoline and other light distillate formed as a resultof such a process contains substantial quantities of constituents whichare capable of inhibiting the formation of oxygenated bodies and thatthe amount of such constituents formed as a result of the process issubstantially in excess to that necessary to stabilize the gasoline orother light distillate formed as a result of the process.

While the exact nature of the oxidation inhibitor constituents formed asa result of the catalytic cracking operation has not been definitelyestablished, it has been found .that the excess of such inhibitors canbe removed from the gasoline or other light distillate by treatment witha basic solution which leads to the conclusion that they are essentiallyacidic in nature, such as phenolic compounds or other hydroxy aromaticmaterials.

It has been further found that the amount of oxidation inhibitor formedas a result of the catalytic cracking process, before outlined, issubstantially in excess of that which is normally .formed as the resultof a conventional thermal cracking process. While the reason for this isnot definitely known, it may be due to the fact that in the catalyticcracking process the catalyst is periodically subjected to oxidizingtreatment during regeneration and that traces of oxygen remaining on thecatalyst at the start of the cracking operation may react with the oilbeing cracked to form hydroxy compounds or other acidic constituentscapable of inhibiting formation of oxygenated compounds. Whatever theexplanation uents than similar constituents formed as a result ofconyentional cracking processes.

Having described the general nature and objects, the invention will bebetter understood by the more detailed description hereinafter in whichreference will be.made to the accompanymay be, it has been found thatproducts produced from the catalytic'cracking process are definitelyricher in oxidation inhibiting constiting drawing which is adiagrammatic illustration of an apparatus suitable for carrying out thepresent invention.

Referring to the drawing, the numeral I0 designates a charge linethrough which the oil to be cracked is introduced into the system. Thischarge oil is preferably a clean condensate stock such as a virgin gasoil. The oil introduced through line II] is forced by means of pump llthrough a preheating coil l2 located in furnace l3 wherein the oil isvaporized and heated to the desired reaction temperature. The preheatedvapors from the heating coil l2 pass through line It to a manifold linei5 having branched lines It and I1 leading to reaction chambers l8 andi9 respectively. Two reaction chambers are shown so that one reactionchamber may be on the cracking cycle while the other is undergoingregeneration.

Cracked products from the reaction chambers [8 or 19 as the case may be,are removed through lines 20 and 21 respectively and passed through line22 to a fractionating tower 23.

Each reaction chamber l8 and I9 contains a mass of catalytic materialsuch as naturally active or activated clays or similar adsorptivesynthetic compounds of silica and alumina. Regeneration of the catalystis accomplished by means of an oxidizing gas such as air diluted with aninert gas introduced through line 24. The regenerating gas introducedthrough line it is forced by means of blower 25 to either of the tworeaction chambers 18 and is through branch lines 25 and 27 respectively.Products of regeneration are removed from reaction chambers 58 and I9through lines 28 and 29 and may be rejected from the system through line30. Ifdesired a portion of the spent regenerating gases after sufficientcooling may be recycled to the inlet as a diluent for the air. Asbefore-mentioned, in the apparatus illustrated one of the reactionchambers is adapted to be on the cracking cycle while the other isundergoing regeneration and the cracking and regenerating cycles will beshifted from one reaction chamber to the other as desired.

-Retuming now to the cracking process, the cracked products introducedinto the fractionating tower 23 are subjected to fractionation thereinto condense insumciently converted products as reflux condensate.Condensate formed in the fractionating tower 23 may be withdrawntherefrom through line 3| and may be rejected from the system as shownor recycled to the inlet side of the heating coil l2 and subjected tofurther cracking treatment.

Products remaining uncondensed in the fracseparated in the receiver 34are removed therefrom through line 35 having a suitable valve forimposing the desired back pressure on the cracking operation.

It will be understood that the present invention is not concerned withthe details of carrying out the catalytic cracking process but isdirected to the treatment of the motor fuel distillate resulting fromsuch a process.

In accordance with the present invention, the. raw liquid distillatecollected in the receiver 34 is withdrawn therefrom and treated with amild alkaline solution such as a weak sodium hydroxide solution topartially neutralize acidic constituents contained in said rawdistillate. As a result of the alkaline treatment, the. acidicconstituents are converted into the corresponding salt. It is preferrednot to completely neutralize the acidic constituents contained in theraw distillate but to retain therein sufllcient of said constituents tostabilize the distillate product against oxygen reactions.

The solution containing the salt of the inhibitor is then separated fromthe distillate and neutralized with a weak acid solution such assulfuric acid, hydrochloric acid, carbon dioxide and the like toreconvert the inhibitor-salts into the inhibitor.

The inhibitor so liberated can be then separated from the neutralsolution either by settling or centrifuging. The inhibitor being heavierthan the neutral solution separates as the bottom layer.

. Referring specifically to the drawing, the raw distillate removed fromthe receiver 3 5 through line 36 is passed to an alkali treating chamber3? wherein it is treated with a weak alkaline solution introducedthrough line 38. The alkali treating chamber may be of any conventionaldesign and may be of a continuous or discontinuous type. The distillateand alkaline solution separates in two phases within the alkali treatingchamber 37. The lighter distillate phase may be removed from the chamberthrough line 39 and the alkaline solution containing the inhibitor saltis removed through line db and passed to a neutralizing chamber 4iwherein it is neutralized with a weak acid solution such as sulphuricacid or hydrochloric acid introduced through line 62. The inhibitorliberated as a result of the neutralizing treatment may be allowed toseparate in the bottom of the neutralizing chamber 4i and can bewithdrawn through line 43.

The product so recovered has been found to be an exceptionally goodinhibitor for suppressing the formation of oxygenated bodies in gasolineand other light hydrocarbon distillates.

The alkali washed distillate withdrawn from the alkali treating chamber37 through line 39 is preferably passed to an acid treating chamber itmore stable.

menses 8B where it is treated with sulphuric acid to remove highlyunsaturated constituents and thereby reduce the acid heat of the productand make From theacld treating chamber 44 the product may be passed to asuitable washer 45 wherein the acid is removed. The resulting productmay be subjected to sweetening or other *flm'shing treatment inaccordance with the common practice. In case the acid and finishingtreatment resultsin removal the natural inhibitors remaining in thegasoline after the controlled alkali treat,

additional material inhibitors recovered by the alkali treat may beadded to the finished product. For example, a part or all of the naturalinhibitors removed from the neutralizing chamber 4| through line 43 maybe passed through line 46 and blended with the finished product of theprocess.

Theinitial alkali treatment of the raw dis tillate prior to the acidtreatment has a further advantage in that it effects a more completeremoval of sulphur impurities from the gasoline and thereby improves theleadsusceptibility of the product.

The following example may prove helpful for a fuller understanding ofthe invention, it being understood that the values'and conditions theregiven are illustrative rather than limitive.

A catalytically cracked gasoline was first prepared in the followingmanner. A virgin East Texas gas oil having an A. P. I. gravity of 33.4was passed through a reaction zone containing activated clay of the typeknown as Superfiltrol. The rate of feed was 0.5 volume of liquid feedper volume of catalyst per hour and the length of the cracking cyclebetween regenerations was 30 minutes. The temperature within thereaction zone was maintained at 850 F. The products were fractionated toseparate a gasoline distillate having a final boiling point of 418 F.

The gasoline so prepared was then treated with one-fifth its volume of a2% solution of sodium hydroxide. The sodium hydroxide solution was thenseparated from the gasoline and neutralized by treatment with one-tenthnormal sulfuric acid. The inhibitor was allowed to settie in the bottomor the neutral solution and was withdrawn therefrom. The followingtable.

illustrates the properties or the gasoline before and after the alkalitreatment.

original camp Catalytically iytically fi g'g cracked gasone um moval ofinhibitor sac 67.8 +4 +6 11 234 s. 2 a a so 50 91 91 7a a 19. o s1 89Percent c. 158.. 26. 0 26. 5 Percent c. 212. 44. 0 43. 5 Final, F 418420 The breakdown time listed in the above table was determined by themethod described by Winning and Thomas in an article appearing in theIndustrial 8: Engineering Chem. vol. 25 page 5111 (1933) and the copperdish gum test was Federal Specifications accuses treatment, it will benoticed that the only important change in the characteristics is thedrop in the breakdown time from ll to 2 /4 hours. Inasmuch as thebreakdown of 2%, is sumciently stable to meet all practical requirementsand specifications, the inherent properties of the gasoline remainunimpaired by the alkali treatment. Not only is the gasoline unimpaired,but the odor thereof is materially improved by removal of the excessinhibitors contained therein.

The inhibitor prepared as above described when added to thermallycracked gasoline in 6.2% concentration increased the breakdown time from1 /2 hours to 8 hours. It will thus be seen that the inhibitor recoveredfrom the catalytically' cracked gasoline is extremely potent forsuppressing reactions between oxygen and gasoline.

of removing the excess natural inhibitors from the cataiytically crackedgasoline by means of the alkali treatment previously de-.

scribed, such gasoline may be used directly as a blending agent inunstable motor fuels such as thermally cracked gasoline, gasoline etherblends and the like so that the excess natural inhibitors present in thecatalytically cracked gasoline may be employed as an inhibitor for theunstable portion of the blend.

Having described the specific embodiment and given a specific examplethereof, it will be understood that the invention covers such othervariations and modifications as come within the spirit thereof. It willbe further understood that it is not my intention to unnecessarilyrestrict the invention except as necessary to adequately distinguishfrom prior art.

I claim:

1. A method of producing inhibitors capable of suppressing the oxidationof hydrocarbon distillates which comprises subjecting a high-boilinghydrocarbon oil to cracking in vapor form in the absence of anysubstantial amount of free oxygen in the presence of an adsorptivecracking catalyst, periodically regenerating said catalyst with anoxidizing gas, fractionating the cracked products to separate a lightdistillate product therefrom, treating said light distillate productwith a weak solution of sodium hydroxide, separating the sodiumhydroxide solution distillate, and neutralizing the sodium hydroxidefrom the treated solution separated from said distillate to liberateinhibitors contained therein.

2. A method of preparing inhibitors capable of suppressing the oxidationof hydrocarbon diatillate which comprises cracking high-boilinghydrocarbon oils in the presence of a catalyst comprising activatedclay, periodically regenerating said clay with an oxidizing gas,fractionating the cracked products to separate a light distillateproduct therefrom,'treating said distillate with an alkaline solutioncapable of neutralizing hydroxyaromatic constituents contained therein,separating the alkaline solution from the treated distillate andtreating the alkaline solution so separated to liberate inhibitorscontained therein.

3. A method of refining cracked distillates, obtained by cracking higherboiling oils in the presence of an adsorptive cracking catalyst andwherein the adsorptive cracking catalyst is subjected to periodicregenerations' by oxidation, to

improve the odor of said cracked distillates and to recover oxidationinhibitors therefrom which comprises treating said distillate with analka line solution capable of neutralizing hydroxyaromatic constituentscontained therein to form a salt, separating the alkaline solutioncontaining said salt from the treated distillate and treating thealkaline solution so separated to liberate hydroxyaromatic constituentscontained therein.

4. A method of producing a stable motor fuel of high anti-knockproperties which comprises cracking higher boiling oil into motor fuelconstituents in the presence of a solid catalyst, periodicallyregenerating said catalyst in situ with an oxidizing gas, treating theraw motor distillate from the process with an alkali solution capable ofreacting with the hydroxyaromatic constituents contained therein to forma salt, separating the alkali solution containing the said salt from thedistillate so treated, treating the alkali solution to decompose thesalt to liberate oxidation inhibitors therefrom, further treating thealkalitreated distillate with acid to remove highly unsaturatedconstituents therefrom and. thereafter adding to the acid-treatedproduct at least a portion of the oxidation inhibitors liberated fromthe alkali solution.

. JOSHUA A. TILTON.

